Normal peripheral blood usually contains five types of leukocytes, that is, lymphocytes, monocytes, eosinophils, neutrophils, and basophils, in predetermined ratios. Whether the ratios of these components present in the blood are normal can be determined by counting and classifying the leukocytes in the blood.
When disease is present, various phenomena arise such as the classification ratios of the leukocytes change and abnormal cells appear. For example, when an inflammatory response occurs in vivo due to bacterial infection or the like, there is an increase in the ratio of immature leukocytes and there are also increases of stab neutrophils with unlobed nuclei and segmented cells with few segmented nuclei. Effective information for determining whether disease is present can therefore be obtained by classifying and counting leukocytes.
For example, Japanese Laid-Open Patent Publication No. 2006-91024 and U.S. Pat. No. 6,842,233 disclose methods for classifying and counting normal leukocytes and classifying and counting immature leukocytes. U.S. Pat. No. 5,050,987 and U.S. Pat. No. 5,047,963 disclose particle analyzers for extracting the complexity of the particle signals of a leukocyte and determining the number of lobes of a nucleus. Japanese Laid-Open Patent Publication No. 9-274041 discloses a method for measuring CRP concentration in blood without centrifuging the collected blood. United States Patent Publication No. 2007/0133855 discloses a pattern-matching apparatus capable of searching similarities in leukocyte particle patterns.
The methods disclosed in Japanese Laid-Open Patent Publication No. 2006-91024 and U.S. Pat. No. 6,842,233, however, require a device for classifying and counting normal leukocytes and a separate device for classifying and counting immature leukocytes. The analyzers disclosed in U.S. Pat. Nos. 5,050,987 and 5,047,963 require complex signal processing, both blood analyzers have complicated structures that are difficult to make more compact and light weight, and are difficult to make less expensive. Japanese Laid-Open Patent Publication No. 9-274041 also requires a device for counting normal leukocytes, and measuring CRP by a special immunological measuring method that requires reagents and devices. Of course, CRP measurement and leukocyte measurement can be performed by commercial apparatuses, but the aspect of requiring immunological reagents for the CRP measurement remains unchanged.